MANUFACTURERS are increasingly turning to soy to create bio-based products, but with a growing awareness of the carbon footprint of production processes, companies want more information on the environmental impact of feedstocks.
A new peer-reviewed study funded by the United Soybean Board and soybean checkoff updates the data used in conducting lifecycle assessments of industrial products made from domestically produced soybeans.
Soy is used as an ingredient in a wide range of bio-based products - from biodiesel in vehicles to resins in the exterior panels of cars and farm machinery to spray foam insulation for buildings to lubricants that have many uses (Flowchart).
A key objective of the new study was to update lifecycle inventory (LCI) databases for soybean production, processing and conversion into four key soy-derived feedstocks - methyl soyate, soy lube base stock, soy polyol and soy resin - that are used in fuel and industrial products.
The study's cradle-to-gate scope begins with soybean farming (the cradle) and goes through processing products (the gate).
Currently, data included in the US Department of Energy's "US Life Cycle Inventory" is based on just three years, from 1998 to 2001. The updated project is based on US agricultural data for the 2001-07 period and also contains previously unavailable data on soybean processing, or crushing.
Omni Tech International Ltd conducted the study for the Soybean Board. Four Elements Consulting LLC performed the lifecycle assessment modeling. A group of international reviewers verified the project in accordance with ISO 14040/44 Life Cycle Requirements.
Environment al benefits
Jim Pollack, project manager for the study, said one of the major findings was the reduced amount of energy needed to grow soybeans and convert them into meal and oil.
The updated data show that soybean farming requires approximately 20 per cent less direct energy due to reduced diesel and gasoline usage, which is predominantly the result of an increase in conservation tillage and adopting biotechnology, allowing for fewer tractor passes across the field. Soybean processing facilities reduced their energy consumption 45pc compared to 1998 DOE data.
Pollack said as the price of energy rose, producers and processing plants became more conscious of energy use and increased efficiencies.
The study identifies significant greenhouse gas reductions from soybean production. As soybeans grow, they remove greenhouse gases from the atmosphere. The 3.36 billion bu. of soybeans grown in the US in 2009 removed the carbon equivalent of taking 21 million cars off the road (when figures are computed using the Environmental Protection Agency's Greenhouse Gas Equivalencies Calculator).
In addition, the calculated release of the greenhouse gas nitrous oxide is 85pc less than the data contained in the current US LCI database due to a corrected emission factor the U.N.'s International Panel on Climate Change issued in 2006.
Soybean yields are on the rise; the average yield for 2004-07 was 42.3 bu. per acre - a 12pc increase over data used in the LCI database.
This is consistent with other analyses that found that plant breeders have increased the yield potential of soybeans an average of 0.41 bu./acre per year for the past 35 years. Meanwhile, plant breeding companies anticipate that new soybean varieties will allow for yield increases of 40pc in the next decade.
Putting it to work
As part of the new study, a lifecycle impact assessment was completed using the updated LCI information for each of the four soybean-derived feedstocks.
These assessments found that each feedstock significantly reduced greenhouse gas emissions and had lower fossil fuel depletion impacts compared to its petroleum-based counterpart.
The study can be an important resource for companies that want to update lifecycle assessments of their specific products made using US soy.
"This profile is the first comprehensive lifecycle study covering US soybean production through four major bio-based products," said John Cooper, Soybean Board director and member of its Domestic Marketing Committee. "US soy already delivers environmental and energy benefits. It's exciting to see the trends point to even more in the future."
One of the most common soy-based products is biodiesel. To date, however, the numbers behind energy costs and environmental impact have been more theoretical than based on actual data, according to Pollack.
In cooperation with the National Oilseed Processor Assn. and National Biodiesel Board, researchers took data from 80pc of the nation's plants and made a generic plant by weighting energy inputs and efficiencies.
The research found that biodiesel production facilities have reduced their energy consumption 27pc compared to the 1998 DOE data. It also documented that biodiesel producers are implementing more water-saving technologies and selling more glycerin (a by-product) into high-grade markets. Biodiesel has even further benefits when considering the emission reductions of using it to fuel a vehicle.
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